A micro-machined Pirani gauge for vacuum measurement of ultra-small sized vacuum packaging

Abstract Quite a few MEMS devices need vacuum packaging technology to guarantee the desirable performance. Developing an absolute vacuum environment for those devices is indispensable. However, it is difficult to monitor the pressure change in vacuum chamber in on-line and real-time mode. A surface micro-machined Pirani gauge for measuring vacuum pressure inside vacuum packaging in wafer level was presented in this paper. It was designed with a simplified structure and did not need complex circuit. Only a simple Wheatstone bridge circuit is needed, which could be manufactured by conventional CMOS processes. Preliminary tests on this device were conducted. The experimental results show that the Pirani gauge is capable of measuring pressures from atmospheric value to 1 Pa and has a very good linearity in the range from1 Pa to 300 Pa. It demonstrates that the micro-machined Pirani gauge has great potential to be used in wafer level vacuum packaging. Also, the Pirani gauge is able to be the packaging hermeticity detector.

[1]  Honghai Zhang,et al.  Vacuum measurement on vacuum packaged MEMS devices , 2007 .

[2]  Haluk Kulah.  Closed-loop electromechanical sigma-delta microgravity accelerometers. , 2003 .

[3]  B. Khuri-Yakub,et al.  Surface micromachined capacitive ultrasonic transducers , 1998, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[4]  Albert M. Leung,et al.  The nanogap Pirani-a pressure sensor with superior linearity in an atmospheric pressure range , 2009 .

[5]  Jin-Shown Shie,et al.  Characterization and modeling of metal-film microbolometer , 1996 .

[6]  Jin-Shown Shie,et al.  A sensitive Pirani vacuum sensor and the electrothermal SPICE modelling , 1996 .

[7]  Jin-Shown Shie,et al.  High performance Pirani vacuum gauge , 1995 .

[8]  K. Khosraviani,et al.  The nanogap pirani - a pressure sensor with superior linearity in atmospheric pressure range , 2008, 2008 IEEE 21st International Conference on Micro Electro Mechanical Systems.

[9]  Khalil Najafi,et al.  A micromachined Pirani gauge with dual heat sinks , 2005 .

[10]  Butrus T. Khuri-Yakub,et al.  Fabrication and characterization of surface micromachined capacitive ultrasonic immersion transducers , 1999 .

[11]  S. H. Choa,et al.  Reliability of vacuum packaged MEMS gyroscopes , 2005, Microelectron. Reliab..

[12]  Douglas Ray Sparks,et al.  Wafer-to-wafer bonding of nonplanarized MEMS surfaces using solder , 2001 .

[13]  Carlos H. Mastrangelo,et al.  Microfabricated thermal absolute-pressure sensor with on-chip digital front-end processor , 1991 .

[14]  Ashwin A. Seshia,et al.  A vacuum packaged surface micromachined resonant accelerometer , 2002 .

[15]  Dexiu Huang,et al.  Getter free vacuum packaging for MEMS , 2009 .

[16]  Emile Martincic,et al.  Micro Pirani vacuum gauges manufactured by a film transfer process , 2010 .

[17]  K. Najafi,et al.  Vacuum packaging technology using localized aluminum/silicon-to-glass bonding , 2002, Technical Digest. MEMS 2001. 14th IEEE International Conference on Micro Electro Mechanical Systems (Cat. No.01CH37090).

[18]  Khalil Najafi,et al.  A doubly anchored surface micromachined Pirani gauge for vacuum package characterization , 2003, The Sixteenth Annual International Conference on Micro Electro Mechanical Systems, 2003. MEMS-03 Kyoto. IEEE.

[19]  Fengtian Zhang,et al.  A micro-Pirani vacuum gauge based on micro-hotplate technology , 2006 .